Nuke them first. But corn cobs I would say are pretty pest free especially if you are collecting them from corn you eat off the cob.Yeah chopped up corn stalks are used succesfully as bulking agents in composting manure and even biosolids. I guess those would work too, but I have no ideea if those invite pests when used indoors..
Depends what type of a soil you have there.How much biochar would be good for a garden bed that never got any? And do I stop using perlite or I add both?